304 ORDER FLAGELLATA-PANTOSTOMATA. 



be at such an angle that, as shown at Plate XV. Fig. 67, the basal flexure and terminal 

 portion may appear to be separate structures, the former presenting an independent 

 knob-like aspect. Lastly, where the distal lengths of the flagella and their basal 

 flexures are both in focus, and apparently continuous with each other, these flexures 

 may be coiled so closely beneath the anterior region of the animalcule's body, as to 

 present the aspect of fusiform or pyriform inflations of the basal region of the 

 flagella, as first interpreted by the two authorities here quoted. When the animalcules 

 are treated with osmic acid or iodine, they roll over and over helplessly in the water, 

 every portion of their organization being brought successively into focus, and the true 

 significance of the previously imperfectly observed phenomena, as here explained, 

 may easily be verified. Figs. 68 and 69 of the accompanying plate are delineated 

 from examples submitted to tliis treatment. The two anterior so-called " snapping 

 eye-like structures " reported by Messrs. Dallinger and Drysdale of this type, were 

 immediately identified by the author with the normally developed and highly 

 characteristic contractile vesicles. 



Stein includes a long series of figures of this species in his recently published 

 volume, the same, however, apparently containing but litde that is new. One or more 

 dark, granular, eye-like pigment-spots are shown in some, but not in all, of these 

 figures, such spots being moreover located indifterently in separate animalcules at 

 either the anterior or posterior extremity of the body. No indication of the charac- 

 teristic loop-like flexure of the flagella or of the possession by the animalcules of 

 a capacity to attach themselves, as here recorded, is given in Stein's figures or 

 accompanying index. 



The two forms described by Perty under the respective names of Polytoma 

 ocdlata and P. virens, cannot be regarded as otherwise than local or transitional 

 variations of P. tivella. Diesing, nevertheless,* has proposed to institute a new generic 

 and specific title, Glenopolytoma typicum for that variety, P. ocellata, in which a red 

 pigment-spot is present at the anterior extremity. 



Fam. XII. PSEUDOSPORIDiE, S. K. 



Animalcules naked, repent or natatory ; flagella tvi^o in number, of even 

 size ; no distinct oral aperture. 



Genus I. PSEUDOSPORA, Cienkowski. 

 Animalcules free-swimming or repent, plastic and changeable in form, 

 typically more or less ovate or globose ; the anterior extremity bearing 

 two long, equal-sized flagella ; food incepted at any point of the periphery ; 

 endoplast and contractile vesicles conspicuous. 



The Pseudospora volvocis only of Cienkowski is retained in the present genus, 

 the two other forms, referred to it by that authority under the titles of Pseudospora 

 parasitica and P. nitdlarum, being in no way distinct from the ordinary members of 

 the genus Monas, to which they are here referred. Food-particles would appear to 

 be incepted at any point of the periphery, otherwise the features afforded by the 

 plasticity of the body-sarcode and character of the flagella correspond considerably 

 with those exhibited by the stomatode genus Zygosdmis. 



Pseudospora volvocis, Cienk. Pl. XV. Figs. 42 and 43. 



Body ovate or globose, often amoebiform ; flagella fine, equal in size, 

 exceeding- the body in length ; contractile vesicles minute, three in number, 

 scattered; endoplast spherical, subcentral. Length 1-1250". 



Hab. — Fresh water, as a parasite of Volvox globator. 



* * Revision der Prothelminthen, ' 1866. 



